The present invention relates to analytical apparatus, and more particularly to analytical furnaces.
A wide variety of analytical furnaces have been developed to test material samples under controlled temperature and environmental conditions. Such furnaces are used, for example, to perform ash fusion tests by inserting the ash samples into the furnace; ramping the temperature within the furnace chamber; and observing the samples to determine the various deformation temperatures of the ash.
One known analyzer includes a generally cylindrical furnace, defining a furnace chamber and including a floor having an aperture communicating with the chamber. The analyzer further includes a sample-supporting platform generally concentrically aligned with the furnace floor aperture and vertically shiftable between an analyzing position, wherein the platform is located within the furnace, and a loading position, wherein the platform is located below the furnace. The platform is relatively difficult to load and unload because the platform, even in the loading position is located directly under the furnace. Consequently, samples may be placed on and removed from the platform only by reaching underneath the furnace and more particularly between the lowered platform and the furnace floor. The typical location of the furnace and sample platform in a rear portion of the analyzer further complicate sample handling.
Analytical furnaces of the resistance type include a plurality of electric heating elements extending through the furnace wall and into the furnace chamber. Usually, the furnace includes a removable cover, and the heating elements extend between the upper surface of the furnace side wall and the cover. However, the apertures, channels, or bores required to accommodate the heating elements permit air within chamber to exit the furnace relatively rapidly. This makes furnace temperature regulation difficult and increases the furnace power requirements, and cost of operating the analyzer. Although gaskets have been positioned between the heating elements and various portions of the furnace in an attempt to seal the heating elements within the furnace, these gaskets are relatively fragile and easily broken. Further, the gaskets are typically ring-shaped members which may be positioned in only one fixed position between the upper surface of the furnace wall and the furnace cover.